This invention relates to the placement of optical fiber cable (OFC), coaxial cable and twisted pair telephone cable in conduit, and more particularly to improved motor vehicle mounted apparatus for and method of placing optical fiber cable in subduct that was previously placed in an underground duct-type conduit.
Techniques are constantly being devised for pulling longer continuous lengths of optical fiber cable. In the more advanced techniques, flexible one inch diameter polyethylene pipe or subduct is pulled into four inch diameter underground duct pipes. The subduct is connected so that it runs continuously between an input manhole and an output manhole. After blowing a light weight fish line through the subduct, a pulling line is pulled through the subduct and connected with a pulling sock to the free end of an optical fiber cable on a reel that is located adjacent the input manhole. The other end of the pulling line is connected to some sort of pulling apparatus at the output manhole. During pulling of the cable a liquid lubricant such as vasoline, hydralube blue, or silicone is introduced into the input end of the subduct along with the cable. The pulling tension must be maintained less than a maximum value such as 600 pounds to prevent damaging the cable. Although motor vehicle mounted cable pulling apparatus is currently available, much of it is expensive and not convenient to use. Some cable pulling apparatus is so large and bulky that it dictates that a truck be dedicated to this application. Other cable pulling apparatus that is located on the bed of a truck is large and cumbersome and must be physically unloaded from the truck by several people or with a fork lift and then set up next to the output manhole. Such equipment is difficult and expensive to use, and is not convenient to use where the output manhole is in an unimproved area. Trailer mounted pulling apparatus also suffers from the latter disadvantage. And a cable pulling technique which employs the take-up reel on a telephone line truck to pull the cable requires that a very expensive motor vehicle be utilized in this application. Although portable cable pulling apparatus such as that described in the brochure HCPU-1 Light Guide Pulling System, manufactured by Hydraulic Energy Company of San Rafael, Calif. is relatively light such that it can be readily transported on a truck and carried up to a manhole, it requires considerable setup time and is relatively unstable compared to equipment that is mounted on a fixed pallet structure or a truck.
An object of this invention is the provision of improved motor vehicle mounted apparatus for pulling optical fiber cable.